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JWST observed the young galaxy GS-10578 starved to death by its supermassive black hole. | Credit: JADES Collaboration
Astronomers have discovered that a young galaxy was slowly starved of its central supermassive black hole, effectively a cosmic “death by a thousand cuts”.
James Webb Space Telescope (JWST) and the Atacama Large Millimeter/Submillimeter Array (Alma) studied this ill-fated galaxy, calling it GS-10578 or the slightly snappier nickname “Pablo’s Galaxy” in honor of the first astronomer to study it in detail. Light from Pablo’s galaxy took about 11 billion years to reach us, meaning JWST and ALMA allow astronomers to see it as it was just 3 billion years later. Big Bang. For such an early galaxy, it is unusually large, containing as much mass as about 200 billion Suns.
Most of the stars in Pablo’s galaxy appear to have formed between 12.5 billion and 11.5 billion years ago. However, this galaxy appears to have stopped forming stars and has exhausted its supply of cool star-forming gas despite its relatively young age. As astronomers define the end of star formation and the transition to quiescence as the “death” of a galaxy, this means that Pablo’s galaxy “lived fast and died young.”
The team behind this study released the results for the first time about Pablo’s return to the galaxy September 2024Using JWST alone, finding that Supermassive black holes At its heart is a huge mass of gas pushing at 2.2 million miles per hour (3.5 million km/h). This is enough to allow star-forming matter to completely escape the gravitational influence of Pablo’s galaxy.
Adding ALMA, an array of 66 radio telescopes located in the Atacama Desert region of northern Chile, the researchers observed Pablo’s galaxy for an additional seven hours in search of carbon monoxide, which they can use as a way to trace the cold hydrogen gas that forms stars. However, this search came up empty-handed.
But it was telling in itself.
“We were surprised by how much you can learn without seeing anything,” said team member Jan Scholtz of the University of Cambridge in the UK. said in a statement. “Even with ALMA’s deep observations of this type of galaxy, there was essentially no cold gas left. This points to slow starvation rather than a single dramatic death blow.”
Meanwhile, an additional 6.5 hours of observations with JWST revealed that Pablo’s galaxy is losing about 60 solar masses to gas each year. At that rate, the galaxy’s fuel for star formation could run out in between 16 million and 220 million years. If this seems like an incredibly long period of time, scientists estimate that it usually takes as long as a billion years for such a galaxy to exhaust its fuel for star-formation.
“The Milky Way appears to be a quiescent, rotating disk,” said team co-leader Francesco D’Eugenio of the Cavalli Institute for Cosmology. “This tells us that it did not suffer a massive, disruptive merger with another galaxy. Yet it stopped forming stars 400 million years ago, while the black hole is still active.
The team reconstructed the star formation history of Pablo’s galaxy, finding that the fresh gas was being pushed out by the black hole, preventing it from returning to the galaxy. This prevents refilling of the “fuel tank” for star birth. They also discovered that the supermassive black hole in this young galaxy does not expel all of its gas at once, but is experiencing repeated cycles of gas expulsion.
“So the current black hole activity and the outbursts of gas we’ve seen didn’t cause the shutdown; rather, repeated episodes may have prevented the fuel from coming back in,” D’Eugenio added.
The team’s findings may help explain why JWST has discovered so many old-looking galaxies in the early universe.
“You don’t need a single cataclysm to stop stars forming galaxies, just keep fresh fuel from coming in. Before the Web, these were unheard of,” Scholtz said. “Now we know they’re more common than we thought – and this starvation effect may be why they live faster and die younger.”
With the effectiveness of the ALMA/JWST telescope tag-team, astronomers hope that further observations of Pablo’s galaxy can reveal more about the mechanisms used by supermassive black holes to starve the galaxy prematurely.
The team’s research was published Tuesday (Nov. 25) in the journal Nature Astronomy.
